Confined Current Path (CCP)-CPP Spin-Valve Structure: Preliminary Experiment and Two-Current Model Analysis

Abstract

A current-perpendicular-to-the-plane (CPP) spin-valve element structure specifically devised for high-density magnetic recording over 100G bits/in2, named a CCP-CPP spin valve, was studied both by experiment and by simulation. One or more current-confining (CC) layers are included in the structure so that its resistance may exhibit a high enough resistance to be applicable to read heads. A micro-structured sample with a nominal area of 50μm2, fabricated by means of multi-step photolithography using a multilayer of Si/SiO2 (200nm)/Cu (150nm)/CoFe (6nm)/SiO2 (0.3nm)/Cu (3nm)/CoFe (5nm)/IrMn (15nm)/Cu (50nm), showed a high ΔR-value (the resistance change due to the GMR effect) of 10mΩ, although the GMR ratio was only 0.25%. Simulation performed by using a combination of an equivalent resistor-network model and Mott's two-current model has suggested that insertion of a CC-layer on each side of the spacing conducting-layer would enhance both ΔR and the GMR ratio substantially.